Mini-truss thin-sheet panel assembly

ABSTRACT

A mini-truss thin-sheet panel assembly, in one embodiment, a substantially rigid thin-sheet panel assembly having a non-rigid thin-sheet component includes the thin-sheet component which has selected plan area and shape, a hacker having a plan shape and area substantially similar to the thin-sheet component, and plural riser elements of selected height and configuration each extending from the backer to distal ends connected to a reverse surface of the thin-sheet component, the riser elements being configured and disposed in an array which causes the assembly to have substantial rigidity in a selected direction in the thin-sheet component.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to and the benefit of U.S. ProvisionalApplication No. 60/999,833, filed on Oct. 18, 2007, the entire contentof which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to a thin-sheet panel assembly,and more particularly to a mini-truss thin-sheet panel assembly adaptedfor use in solar collector applications.

BACKGROUND OF THE INVENTION

Solar collection facilities utilize solar concentrators and/orphotovoltaic panels for harnessing solar energy. Solar concentratorassemblies (SCAs) utilizing movable parabolic trough collectors presentlarge reflective surface areas (apertures) for tracking the sun andfocusing the captured radiant energy on linear heat collection elements(HCEs) as a first step in a thermomechanical conversion process forgenerating electrical power. A solar-trough solar power generationfacility typically includes many SCAs arranged in rows to capture greatamounts of solar radiant energy.

The reflective surfaces of troughs of SCAs are usually hot-formed,thick-glass mirrors that ideally conform to a given geometry, notablysurface curvature. Operating efficiency of the solar plant is largelydependant on the ability of the mirrors to maintain surface curvatureaccuracy so that the mirrors sharply focus reflected sunlight on theHCE. This requires very exacting manufacturing processes for mirrorproduction and high rigidity of the mirrors themselves as mounted totheir supports. Thus, the glass is typically formed thicker, oftenresulting in a mirror weight that rivals the weight of the supportingstructure.

Traditionally, hot-formed, glass mirrors are used in various solarconcentrating applications, such as the Nevada Solar One solar powergenerating plant in Nevada. The glass mirror material is hot-formed tothe mathematical shape (surface geometry) required to reflect andconcentrate sunlight on an HCE. Such hot-formed glass is also known assagged glass. Sagged glass is thick, heavy, costly to manufacture,costly to transport and install at a facility, and prone to breakage.

The thick glass mirrors (or any other reflectors utilized) must retaintheir mathematical shape in order to efficiently focus concentratedsunlight, which requires the hot-formed mirror glass to have asufficient thickness to maintain the mirror shape (usually about threeto five millimeters). Problems with the hot-formed glass include thatthe thicker glass reduces the reflective efficiency of the mirror (moreabsorption and less reflection of sunlight), has fabrication-relatedsurface error limitations (slope error and edge effects), is more costlydue to the increased amount of glass material, and is heavier resultingin undesirable shipping and handling issues. Additionally, thick sheetmaterial is difficult to form in the complex shapes needed for solarpower applications and may trap water in the interface which corrodesthe silvering.

In some cases, thin-glass and thin-film have been bonded directlyagainst a pre-formed substrate or aluminum plate having a desiredcurvature, or to a sandwich panel made with the required surfacegeometry. Sandwich panels are usually comprised of two sheet metalsurfaces bonded to a cellular core such as a honeycomb configuration.Historical problems with thin-glass and thin-film bonded directlyagainst a pre-formed curved substrate or plate, or in combination withhoneycomb and other types of closed-cell panel construction, are highcost and their affinity for water intrusion when exposed to weather.Trapped water attacks the preferably aluminum components and penetratesthe mirror coatings, causing the mirror silvering to corrode.

SUMMARY OF THE INVENTION

Aspects of embodiments of the present invention are directed to amini-truss thin-sheet panel assembly. In embodiments of a mini-trussthin-sheet panel assembly according to the present invention, the“mini-truss” design of a backing material element is important toproviding rigidity to the mini-truss thin-sheet panel assembly.Embodiments of the mini-truss thin-sheet panel assembly maintain a thinpanel, such as a thin sheet of glass or other reflective material, in arigid or substantially rigid configuration. Further, embodiments of themini-truss thin-sheet panel assembly of the present invention may beutilized in solar collector troughs of a solar concentrator assembly(SCA), for example.

An aspect of embodiments of the mini-truss thin-sheet panel assemblyaccording to the present invention, as utilized in an SCA, for example,is lighter weight and less costly reflective surfaces. For example, athin-glass panel of a mini-truss thin-sheet panel assembly, according toan embodiment of the present invention, may have about one fourth of thethickness and weight of sagged glass, and may be manufactured in a flatconfiguration without hot-forming (but may later be “cold formed” to adesired shape or curvature) and, therefore, may be manufactured at lesscost. Another aspect of embodiments of the mini-truss thin-sheet panelassembly is the “cold” formability of the thin-glass or thin-film. Yetanother aspect of embodiments of the mini-truss thin-sheet panelassembly is greater overall mirror rigidity and, therefore, improvedaccuracy as utilized in an SCA, for example. Still another aspect ofembodiments of the mini-truss thin-sheet panel assembly is increasedease of installation. Still another aspect of embodiments of themini-truss thin-sheet panel assembly is reduced transportation costs.Still another aspect of embodiments of the mini-truss thin-sheet panelassembly is elimination or reduction of secondary breakage, such as mayresult from heavy wind forces applied against thick-glass structures.Still another aspect of embodiments of the mini-truss thin-sheet panelassembly is interchangeability with or use in combination with existingsolar troughs or other devices. Still another aspect of embodiments ofthe mini-truss thin-sheet panel assembly is improved reflectiveperformance. Still another aspect of embodiments of the mini-trussthin-sheet panel assembly is a substantially open architecture forallowing moisture to drain or evaporate and thereby prevent or deter theaccumulation of moisture between components of the assembly.

According to one embodiment, a substantially rigid thin-sheet panelassembly having a non-rigid thin-sheet component includes the thin-sheetcomponent which has selected plan area and shape, a backer having a planshape and area substantially similar to the thin-sheet component, andplural riser elements of selected height and configuration eachextending from the backer to distal ends connected to a reverse surfaceof the thin-sheet component, the riser elements being configured anddisposed in an array which causes the assembly to have substantialrigidity in a selected direction in the thin-sheet component.

In one embodiment, the riser elements are of substantially uniformheight from the backer so that the thin-sheet component and the backerhave essentially concentric curvature. In one embodiment, an obversesurface of the thin-sheet component has concave curvature. In oneembodiment, the concave curvature is parabolically cylindrical concavecurvature.

In one embodiment, the selected direction is a circular directionsubstantially concentric to the center of area of the thin-sheetcomponent. In one embodiment, the selected direction is at least one oftwo orthogonal directions in the thin-sheet component.

In one embodiment, the thin-sheet component includes a glass layer. Inone embodiment, the thin-sheet component includes structural fibers forproviding strength to the thin-sheet component.

In one embodiment, the backer is defined by a backer sheet, and theriser elements are defined by portions of the backer sheet that are bentaway from the backer sheet and have integral connections to the backersheet. In one embodiment, the portions of the backer sheet that definethe riser elements have substantially triangular configurations and theintegral connections of the riser elements to the backer sheet are atbases of the triangular configurations. In one embodiment, the integralconnections of the riser elements to the backer sheet are spaced alongsubstantially parallel lines, and the riser elements are insubstantially parallel planes. In one embodiment, the parallel planesare in first and second groups, the parallel planes in the first groupbeing substantially normal to the parallel planes in the second group.In one embodiment, the riser elements at their distal ends defineconnection tabs disposed laterally of the heights of the risers. In oneembodiment, the backer sheet includes aluminum.

In one embodiment, the backer is defined by a first backer sheet and asecond backer sheet, and the riser elements are defined by portions ofthe first backer sheet that are bent away from and have integralconnections to the first backer sheet and portions of the second backersheet that are bent away from and have integral connections to thesecond backer sheet, the portions of the first and second backer sheetsthat define the riser elements having substantially triangularconfigurations, the integral connections to the first and second backersheets at bases of the triangular configurations, the integralconnections to the first backer sheet spaced along substantially firstparallel lines, the integral connections to the second backer sheetspaced along substantially second parallel lines, the riser elements ofthe first backer sheet in substantially first parallel planes, the riserelements of the second backer sheet in substantially second parallelplanes, the first parallel lines substantially normal to the secondparallel lines, and the first parallel planes substantially normal tothe second parallel planes.

In one embodiment, the connections of the distal ends of the riserelements to the reverse surface of the thin-sheet component are bondedconnections.

In one embodiment, the thin-sheet component includes a substrate layercomposed principally of a selected synthetic resin material.

In one embodiment, the riser elements include apertures near the distalends.

In one embodiment, the assembly defines a section of a largerparabolically curved cylindrical thin panel. In one embodiment, thebacker has a curvature different from a curvature of the thin-sheetcomponent. In one embodiment, the curvature of the backer issubstantially flat.

In one embodiment, the thin-sheet component is reflective ofelectromagnetic radiation. In one embodiment, the thin-sheet componentis reflective of solar radiation.

In one embodiment, the thin-sheet panel assembly has a substantiallyopen architecture configured to allow moisture to drain or evaporatetherefrom and deter accumulation of moisture in the thin-sheet panelassembly.

According to another embodiment, a support structure for supporting athin panel to have a substantially rigid configuration includes a backersheet, and a plurality of riser elements having heights extending in afirst direction from proximal ends coupled to the backer sheet to distalends and having lengths along rows in substantially parallel riserplanes, the distal ends of the riser elements being attachable to thethin panel for supporting the thin panel and increasing rigidity of thethin panel in a second direction substantially parallel to the riserplanes.

According to another embodiment, in a solar-trough solar powergeneration facility in which each one of a plurality of curvedreflective surfaces supported by a respective one of a plurality oftrough frames has a selected curvature, and the curved reflectivesurfaces having the selected curvature are configured to direct andconcentrate sunlight onto a receiver, an improvement including asubstantially rigid thin-sheet panel assembly including: a non-rigidthin-sheet component having a first surface; a backer; and plural riserelements of selected height and configuration each extending from thebacker to distal ends connected to a reverse surface of the thin-sheetcomponent, the reverse surface opposite the first surface, the riserelements being configured and disposed in an array which causes theassembly to have substantial rigidity in a selected direction in thethin-sheet component, the first surface of the thin-sheet componentincluding at least a portion of one of the plurality of curvedreflective surfaces having the selected curvature.

According to yet another embodiment, a method of forming a thin-sheetpanel assembly having a thin-sheet component and a backer including aplurality of risers extending from the backer to distal ends includes:applying an adhesive to the distal ends of the risers; attaching thethin-sheet component to the distal ends of the risers via the adhesive;and shaping the thin-sheet panel assembly to have a selected curvaturewhile the adhesive cures from an uncured state in which the adhesivedoes not adhere the thin-sheet component and the backer to one anotherto a cured state in which the adhesive adheres the thin-sheet componentand the backer to one another.

In one embodiment, shaping the thin-sheet panel assembly includes:positioning the thin-sheet panel assembly between a first portion of abonding fixture having a first curved surface and a second portion ofthe bonding fixture having a second curved surface, the first and secondcurved surfaces facing each other and substantially corresponding to theselected curvature; and clamping the first and second portions of thebonding fixture toward one another to restrain the thin-sheet panelassembly therebetween to have the selected curvature while the adhesivecures from the uncured state to the cured state.

Other features and advantages of the present invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings which illustrate, by way of example, thefeatures of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front schematic view of a typical curved truss design;

FIG. 2 is a perspective schematic view of a solar concentrator assembly;

FIG. 3 is a top perspective view of a mini-truss thin-sheet panelassembly according to an embodiment of the present invention;

FIG. 4 is a front view of the mini-truss thin-sheet panel assembly ofFIG. 3;

FIG. 5 is a bottom perspective view of the mini-truss thin-sheet panelassembly of FIG. 3;

FIG. 6 is a detail bottom perspective view of a portion of themini-truss thin-sheet panel assembly of FIG. 3;

FIG. 7 is a top perspective view of a backer of the mini-trussthin-sheet panel assembly of FIG. 3;

FIG. 8 is a top view of the backer of FIG. 7;

FIG. 9 is a front view of the backer of FIG. 7;

FIG. 10 is a detail top perspective view of a portion of the backer ofFIG. 7;

FIG. 11 is a detail top view of a portion of the backer of FIG. 7;

FIG. 12 is a detail front view of a portion of the backer of FIG. 7;

FIG. 13 is a top perspective view of a backer of a mini-truss thin-sheetpanel assembly according to another embodiment of the present invention;

FIG. 14 is a side view of the backer of FIG. 13;

FIG. 15 is a top schematic view of a backer of a mini-truss thin-sheetpanel assembly according to another embodiment of the present invention;

FIG. 16 is a top schematic view of a backer of a mini-truss thin-sheetpanel assembly according to another embodiment of the present invention;

FIG. 17 is a top schematic view of a backer of a mini-truss thin-sheetpanel assembly according to another embodiment of the present invention;

FIG. 18 is a top schematic view of a backer of a mini-truss thin-sheetpanel assembly according to another embodiment of the present invention;

FIG. 19 is a top perspective view of a backer of a mini-truss thin-sheetpanel assembly according to another embodiment of the present invention;

FIG. 20 is a top perspective view of a bonding fixture for shaping amini-truss thin-sheet panel assembly according to an embodiment of thepresent invention;

FIG. 21 is a front view of the bonding fixture of FIG. 20;

FIG. 22 is a side perspective view of the bonding fixture of FIG. 20;

FIG. 23 is a top perspective view of a first portion of the bondingfixture of FIG. 20;

FIG. 24 is a top perspective view of a second portion of the bondingfixture of FIG. 20;

FIG. 25 is a top perspective view of the bonding fixture of FIG. 20 inan open position;

FIG. 26 is a top perspective view of the bonding fixture of FIG. 20,showing a mini-truss thin-sheet panel assembly on a first portionthereof; and

FIG. 27 is a top perspective view of the bonding fixture of FIG. 20,showing a mini-truss thin-sheet panel assembly being shaped therein.

DETAILED DESCRIPTION

In the following detailed description, certain exemplary embodiments ofthe present invention are shown and described, by way of illustration.As those skilled in the art would recognize, the described exemplaryembodiments may be modified in various ways without departing from thespirit and scope of the present invention. Accordingly, the drawings anddescription are to be regarded as illustrative in nature, rather thanrestrictive.

The term “mini-truss,” as used in the preceding summary and thefollowing detailed description and claims of this application, refers toan assembly of members forming a rigid, or substantially rigid,framework.

With reference to FIG. 1, a typical curved truss structure 10 includesan upper chord 12, a lower chord 14, and diagonal elements 16, orlacing. The diagonal elements 16 extend between and connect the upperand lower chords 12, 14 at various locations to provide strength andrigidity to the truss structure 10.

With reference to FIG. 2, a solar concentrator assembly (“SCA”) 20includes a row of parabolic, cylindrically curved, or otherwise curved,troughs 22 for collecting radiant solar energy. The troughs 22 havereflective surfaces for reflecting and focusing the radiant energy on aheat collection tube 25. Each of the troughs 22 is supported by acorresponding trough frame 30, which may be constructed of tubes, bars,extrusions, and/or any other suitable structural members for supportingand maintaining the critical shape of each of the troughs 22 and thereflective surfaces thereon. Each of the trough frames 30 may includetwo torque plates 35, one on either side, for coupling to and supportingthe trough frames 30 on supporting pylons 40. The torque plates 35, may,for example, be coupled to the supporting pylons 40 at bearings 45.

With reference to FIGS. 3-6, a mini-truss thin-sheet panel assembly 100according to an embodiment of the present invention includes a thinsheet 110 and a backer 120 that are attached to one another at variouslocations. The configuration of the mini-truss thin-sheet panel assembly100 provides rigidity to the thin sheet 110 and also maintains the thinsheet 110 in a shape having a desired curvature. For example, thereflective surfaces of the troughs 22 of the SCA 20, described above andshown in FIG. 2, may be embodied as the mini-truss thin-sheet panelassembly 100. As such, the reflective surfaces of the troughs 22 will beconfigured to maintain a selected curvature for focusing solarradiation.

The thin sheet 110 (upper chord), according to one embodiment, is a thinglass sheet. In one embodiment, the thin sheet 110 is non-rigid and hasa glass thickness of about one to two millimeters (about 0.04 to 0.08inches). Alternatively, the thin sheet 110 may include glass of anyother suitable thickness. Moreover, other embodiments of the thin sheet110 may be formed of any thin-gage, non-glass reflective material (see,e.g., U.S. Pat. No. 6,989,924 B1 and 2006/0181765 A1, and similarmaterials), such as a synthetic thin-film material, or a combination ofmaterials, such as a thin-film on a flat sheet metal substrate. In oneembodiment, the thin sheet 110 may be formed of a thin-film material ona substrate having a thickness of about 0.5 to 1.5 millimeters (about0.02 to 0.06 inches), or alternatively, any other suitable thickness.The thin sheet 110 may be formed of a material that is reflective ofelectromagnetic radiation, such as solar radiation. Further, in otheralternative embodiments, the thin sheet 110 may be formed of one or morematerials that are non-reflective, having a suitable thickness for thedesired application. Further, as described further below, a thickness ofthe thin sheet 110 (upper chord) may be selected depending on athickness of a backer sheet (lower chord) of the backer 120.

The thin sheet 110, according to one or more embodiments, may include asecondary structural element such as a thin layer of fiberglass, orsimilarly applied alternative suitable material, that provides relieffor thin glass where tensile loads may become excessive. For example,first structural fibers 112 may be bonded, or otherwise attached, to abottom surface of the thin sheet 110 before the mini-truss thin-sheetpanel assembly 100 is shaped to have a selected curvature. The firststructural fibers 112 are attached to the thin sheet 110 having adirection that is substantially parallel to planes of risers of thebacker 120 (see FIG. 3). Similarly, second structural fibers 114 may bebonded, or otherwise attached, to a bottom surface of the thin sheet 110before the mini-truss thin-sheet panel assembly 100 is shaped to have aselected curvature. The second structural fibers 114 are attached to thethin sheet 110 in a direction diagonal to the first structural fibers112 (see FIG. 3). The second structural fibers 114 may be applied to thethin sheet 110 in substitution of, or in addition to, the firststructural fibers 112.

The first and second structural fibers 112, 114, or a similaralternative structural element, provide strength to thin glass.Moreover, the first and second structural fibers 112, 114 are bonded orotherwise applied to the thin sheet 110 before the mini-truss thin-sheetpanel assembly 100 is shaped to have a selected curvature. As such, whenthe mini-truss thin-sheet panel assembly 100 is shaped to have aselected curvature, the first and second structural fibers 112, 114 willbe placed in tension, and the thin glass will thereby be placed incompression and remain in compression during use of the shapedmini-truss thin-sheet panel assembly 100. This is beneficial becauseglass has optimal strength when in compression.

With further reference to FIGS. 3-6, and also with reference to FIGS.7-12, the backer 120 includes a backer sheet 122 (lower chord). Thebacker sheet 122, according to one embodiment, is formed from aluminumsheet metal having a thickness of about 0.5 to 1.5 millimeters (about0.02 to 0.06 inches). Alternatively, any other suitable material may beused to form the backer sheet 122, including any other suitable sheetmetal or other material having any suitable thickness. Further, athickness of the backer sheet 122 may be selected in cooperation with athickness and structural characteristics of the thin sheet 110 so that,for example, the strengths of the thin sheet 110 (upper chord) and thebacker sheet 122 (lower chord) are substantially balanced.

The backer 120 further includes a plurality of risers 124 (diagonalelements). The risers 124, according to one embodiment, are arranged inmultiple rows, and may be uniformly spaced in a grid or array pattern.Each of the risers 124, according to one embodiment, is integrallyformed from the backer sheet 122 and has a substantiallytriangular-shaped configuration. The risers 124 may be formed byshearing, punching, cutting, water jet, or any other suitable device ormethod for separating the risers 124 from the backer sheet 122, on twosides of the triangular shapes of the risers 124. Further, in theembodiment shown, the risers 124 are folded away from the backer sheet122 at a third side (i.e. a bend line) of the triangular shapes suchthat the risers 124 have a height from a proximal end (the integrallyattached bend line) to a distal end. The risers 124, according to oneembodiment, have substantially uniform heights from the backer sheet122, which may be selected depending on thicknesses of the thin sheet110 and the backer sheet 120. The risers 124 may be folded, or bent,utilizing a progressive die or any other suitable device or apparatus,or alternatively may be folded by hand. When the risers 124 are foldedand extend away from the backer sheet 122, corresponding substantiallytriangular-shaped openings 125 remain in the backer sheet 122.

The rows of the risers 124, in one embodiment, are in substantiallyparallel planes. That is, the fold lines of each of the risers 124 arespaced apart and substantially parallel to one another, and the risers.124 are in planes that are substantially parallel to one another.Further, the risers 124 are in planes that are substantiallyperpendicular to the backer sheet 122. In an assembled embodiment of themini-truss thin-sheet panel assembly 100, the planes of the risers 124are substantially perpendicular to an axis about which a curvature isformed in the mini-truss thin-sheet panel assembly 100 (see FIG. 4). Assuch, the risers 124 will provide stiffness and rigidity to themini-truss thin-sheet panel assembly 100 in a direction that willprevent or reduce any disruption from the selected curvature (e.g., bymirror deflections and/or thermal expansion and contraction), such asafter installation at a solar facility.

Further, according to one embodiment, each of the risers 124 has anadhesive pad 130 (“connection tab”) protruding from the triangular shapeat a distal end of each of the risers 124. The adhesive pads 130 providespaced apart regions of surface area for attaching the risers 124 to thethin sheet 110. Each of the adhesive pads 130 may be formed by bending aportion of each of the risers 124 at a distal end of the riser 124, suchas bending the distal end at an angle of approximately 90 degrees. Assuch, the adhesive pad 130 is substantially perpendicular to the rest ofthe riser 124 and substantially parallel to the backer sheet 120.

Further, in one embodiment, as shown in detail in FIG. 11, each of theadhesive pads 130 has a small aperture 132 to allow an adhesive or otherbonding agent to pass through the aperture 132 to a side of the adhesivepad 130 opposite to the side on which the adhesive is applied andthereby form a mechanical attachment to both sides of the adhesive pad130 (see, e.g., FIG. 6).

With reference to FIGS. 13 and 14, another embodiment of a mini-trussthin-sheet panel assembly according to the present invention includes abacker 140. The backer 140 includes a first backer sheet 141 and asecond backer sheet 142 that are each substantially similar to thebacker sheet 122 of the backer 120 described above. The first and secondbacker sheets 141, 142 are stacked with a lower surface of the firstbacker sheet 141 resting on an upper surface of the second backer sheet142.

The first backer sheet 141 includes a plurality of first risers 143formed in rows, the first risers 143 extending away from andsubstantially perpendicular to the first backer sheet 141, similar tothe risers 124 of the backer 120 described above. The first risers 143may be integrally formed from the first backer sheet 141, such as cutfrom and bent away from the first backer sheet 141 at a bend line toform a corresponding plurality of first openings 144 in the first backersheet 141, similar to the backer 120 described above. Further, in oneembodiment, each of the first risers 143 includes a first adhesive pad145 that is formed by bending a distal end of each of the first risers143.

The second backer sheet 142, similar to the first backer sheet 141,includes a plurality of second risers 146 formed in rows, the secondrisers 146 extending away from and substantially perpendicular to thesecond backer sheet 142. The second risers 146 may be integrally formedfrom the second backer sheet 142, such as cut from and bent away fromthe second backer sheet 142 at a bend line to form a correspondingplurality of second openings 147 in the second backer sheet 142.Further, in one embodiment, each of the second risers 146 includes asecond adhesive pad 148 that is formed by bending a distal end of eachof the second risers 146. Each of the second adhesive pads 148, and alsothe first adhesive pads 145, may include an aperture 149, similar to theapertures 132 of the backer 120 described above, for allowing anadhesive to spread to an opposite surface of each of the first andsecond adhesive pads 145, 148.

As described above and shown in FIGS. 13 and 14, the first backer sheet141 rests on the second backer sheet 142. Further, each of the secondrisers 146 of the second backer sheet 142 extends through one of thefirst openings 144 of the first backer sheet 141. The first and secondbacker sheets 141, 142 are oriented relative to one another such thatthe planes of the first risers 143 are substantially perpendicular tothe planes of the second risers 146. That is, the rows of the firstrisers 143 run substantially perpendicularly to the rows of the secondrisers 146. Such a configuration of the first and second risers 143, 146provides the backer 140 with stiffness in two directions. Both the firstrisers 143 and the second risers 146, in one embodiment of themini-truss thin-sheet panel assembly, are attached to a thin sheet atthe first and second adhesive pads 145, 148, such as via an adhesive.

Alternatively to the backers 120, 140 described above, embodiments of amini-truss thin-sheet panel assembly according to the present inventionmay include a backer having any suitable configuration for maintainingthe thin sheet 110 in a rigid or substantially rigid configuration andhaving a desired curvature. For example, with reference to FIG. 15, abacker 150, according to one alternative embodiment, includes a backersheet 152 having a plurality of risers 154. The risers 154 also havetriangular-shaped configurations, but differ from the risers 124 of thebacker 120 in that the risers 154 have distal ends that terminate ascorners of the triangular configurations, rather than having aprotruding feature, such as the adhesive pads 130 of the risers 124.Further, though not shown in FIG. 15, the risers 154 may be staggered,for example, rather than arranged in regularly spaced rows and columns.

With reference to FIG. 16, another backer 160 includes a backer sheet162 having a plurality of risers 164. As shown in FIG. 16, the risers164 also have triangular-shaped configurations. However, distal ends ofthe risers 164 point in opposite directions in alternating rows.

With reference to FIG. 17, a backer 170 includes a backer sheet 172having a plurality of risers 174. The risers 174 also havetriangular-shaped configurations, but the triangular-shaped risers 174are arranged at substantially right angles to one another in alternatingrows. That is, fold lines of rows of a first group of the risers 174 aresubstantially perpendicular to fold lines of rows of a second group ofthe risers 174. Moreover, the first group of the risers 174 will extendfrom the backer sheet 172 in first group planes, and the second group ofthe risers 174 will extend from the backer sheet 172 in second groupplanes, the second group planes being substantially perpendicular to thefirst group planes. As such, the risers 174 of the backer 170 willprovide rigidity to the mini-truss thin-sheet panel assembly in twodirections.

Further, with reference to FIG. 18, a backer 180 according to anotherembodiment, includes a backer sheet 182 having a plurality of risers 184extending away from the backer sheet. The risers 184 differ from thepreviously described embodiments in that the risers 184 haverectangular-shaped configurations.

With reference to FIGS. 15-18, as described above, the solid lines ofthe riser shapes shown indicate shear or separation lines, whereas thedashed lines represent fold lines where the risers 154, 164, 174, 184are folded or bent away from the backer sheet 152, 162, 172, 182.Further, a backer of a mini-truss thin-sheet panel assembly may includeany suitable combination of arrangements (e.g., radial or circular),shapes, sizes, and/or orientations of the risers, such as a combinationof the riser configurations of the backers 120, 150, 160, 170, 180, asdescribed above.

For example, arrangements and/or orientations of the risers may beselected to either accommodate or resist thermal expansion and/orcontraction. Additionally, in yet another alternative embodiment, amini-truss thin-sheet panel assembly according to the present inventionmay include risers having different heights from one another. In such anembodiment, for example, a thin sheet can be supported to have a desiredcurvature, and a backer sheet from which the risers of varying heightsextend could have a substantially flat curvature.

With reference to FIG. 19, in another embodiment, a backer 190 mayinclude riser elements 194 formed by pressing a backer sheet 192 betweentwo tooling plates having protrusions (e.g., similar to the protrusionsof a waffle iron) so as to form corresponding protrusions that are theriser elements 194 in the backer sheet 192. As such, the riser elements194 may be configured to provide stiffness to the backer 190 (and alsoto the mini-truss thin-sheet panel assembly) in two directions.

Alternatively, according to yet another embodiment of a backer, riserelements may include triangles or other shapes separated and bent awayfrom a backer sheet, as described above with respect to the backer 120,but the riser elements may instead be grouped and the distal ends benttoward one another, such as by bending three or four triangular-shapedrisers to form a pyramid-shaped configuration. A thin sheet may beattached to the distal ends of the riser elements that form the top ofthe pyramid.

Still other embodiments of a mini-truss thin-sheet panel assemblyaccording to the present invention may include a backer that is formedof various elements that are not integral to one another, but rather arecombined by fasteners, adhesive, or any other suitable device. That is,unlike the backers 120, 150, 160, 170, 180, 190 described above, inwhich the risers are formed from portions of the backer sheet, otherembodiments may include riser elements that are separate from a backersheet until they are attached to the backer sheet, such as by anadhesive or fastener. For example, one embodiment of a backer mayinclude a fluted fiberglass panel forming risers (the diagonal elementsof the mini-truss) and a separate flat panel forming the backer sheet(the lower chord of the mini-truss).

To assemble the mini-truss thin-sheet panel assembly 100, the thin sheet110 and the backer 120 are attached to one another via bonding, fusing,adhesives, fasteners, or any other suitable device or combinationthereof. In one embodiment, the thin sheet 110 and the backer 120 areadhered to one another utilizing an adhesive 135. The adhesive 135 maybe an epoxy adhesive, or alternatively, may be any other suitableadhesive material. With reference to FIG. 6, in one embodiment, theadhesive 135 is applied to the adhesive pads 130 of the backer 120. Theapertures 132 of the adhesive pads 130 allow the adhesive 135 to spreadto each side of the adhesive pads 130, thereby providing a strongeradhesion of the thin sheet 110 and the backer 120 to one another.

Further, a computer numerical controlled (CNC) machine may be utilizedto apply the adhesive 135 in selected regions (e.g., the adhesive pads130) of the backer 120. By applying the adhesive 135 to the backer 120utilizing a CNC machine, the adhesive 135 may be applied more quicklyand positioned more accurately, for example.

The adhesive 135 may be cured or otherwise set to an adhering state, orcured more quickly, by putting the mini-truss thin-sheet panel assembly100 in an oven or other temperature-controlling device for any suitableperiod of time until the thin sheet 110 and the backer 120 areadequately (e.g., permanently) adhered to one another.

In order to shape an embodiment of a mini-truss thin-sheet panelassembly according to the present invention to have a selectedcurvature, such as a parabolically cylindrical shape or a portionthereof, any suitable bonding fixture, device, apparatus, or method maybe utilized. With reference to FIGS. 20-24, according to one embodiment,a bonding fixture 200 for shaping a mini-truss thin-sheet panel assemblyto have a selected curvature includes a first portion 202 (e.g., a lowerhalf) (see FIG. 23) and a second portion 204 (e.g., an upper half) (seeFIG. 24). The first portion 202 has a first contoured surface 206 (e.g.,a top surface), and the second portion 204 has a second contouredsurface 208 (e.g., a bottom surface) that is substantially the same butfacing opposite the first contoured surface 206. That is, the first andsecond contoured surfaces 206, 208 have substantially similar radii ofcurvature, but one (e.g., the first contoured surface 206) is concaveand the other (e.g., the second contoured surface 208) is convex suchthat the first and second contoured surfaces 206, 208 are substantiallyequally spaced from one another throughout.

Further, the bonding fixture 200 includes fasteners, or a clamp, vice,or any other suitable device or apparatus, for clamping or drawing thefirst and second portions 202, 204 toward one another with a mini-trussthin-sheet panel assembly (e.g., the mini-truss thin-sheet panelassembly 100) sandwiched therebetween, as shown in FIG. 27. In oneembodiment, the bonding fixture 200 includes bolts 210, washers 211, andwing nuts 212 for clamping the first and second portions 202, 204against the mini-truss thin-sheet panel assembly.

The first portion 202 of the bonding fixture 200, in one embodiment,includes a first panel 216 having the first contoured surface 206 (e.g.,an upper surface of the first panel 216). Similarly, the second portion204 of the bonding fixture 200 includes a second panel 218 having thesecond contoured surface 208 (e.g., a lower surface of the second panel218). Also, with further reference to FIG. 22, the first and secondportions 202, 204 may include ribs 214 for supporting the first andsecond panels 216 and 218 and producing the desired curvatures of thefirst and second contoured surfaces 206, 208.

Attachment of the thin sheet 110 and the backer 120 to one another, aswell as shaping the mini-truss thin-sheet panel assembly 100 to have aselected curvature, may be facilitated utilizing the bonding fixture200. The first and second contours 206, 208 of the respective first andsecond portions 202, 204 of the bonding fixture 200, as described above,conform to the geometric shape or curvature that the mini-trussthin-sheet panel assembly 100 is desired to exhibit. The first andsecond portions 202, 204 of the bonding fixture 200 are separated (seeFIG. 25) by loosening the wing nuts 212 from the bolts 210, or byopening any alternative clamping or fastening device. The backer 120 isplaced on the first portion 202 of the bonding fixture 200. The adhesive135, or any other suitable bonding agent, is applied to the adhesivepads 130 of the risers 124. The thin sheet 110 is positioned on therisers 124 of the backer 120. At this stage, the mini-truss thin-sheetpanel assembly 100 is not yet shaped to have a selected curvature (seeFIG. 26). Alternatively, the adhesive 135 may be applied to the adhesivepads 130 and the thin sheet 110 positioned on the risers 124 of thebacker 120 prior to placing the backer 120 on the first portion 202 ofthe bonding fixture 200.

In order to shape the mini-truss thin-sheet panel assembly 100 to havethe selected curvature utilizing the bonding fixture 200 (i.e. thecurvature of the first and second contoured surfaces 206, 208) thesecond portion 204 of the bonding fixture is drawn toward the firstportion 202 and tightened against the mini-truss thin-sheet panelassembly 100 by tightening the wing nuts 212 (or by clamping anyalternative clamping or tightening device) of the bonding fixture 200(see FIG. 27). After the bonding is complete and the adhesive 135 iscured, the mini-truss thin-sheet panel assembly 100 retains thecurvature or contour of the first and second contoured surfaces 206, 208of the respective first and second portions 202, 204 of the bondingfixture 200.

Although the drawings and accompanying description illustrate anembodiment of a mini-truss thin-sheet panel assembly as applied to asolar collector trough, it will be apparent that the novel aspects ofthe mini-truss thin-sheet panel assembly of the invention may also becarried out by utilizing alternative structures, sizes, shapes, and/ormaterials in embodiments of the mini-truss thin-sheet panel assembly ofthe present invention. For example, in some embodiments of a mini-trussthin-sheet panel assembly according to the present invention, a thinpanel, which has been described above with respect to the mini-trussthin-sheet panel assembly 100 as the thin sheet 110, may not bereflective, but rather, may be formed of an alternative material forpurposes of decoration, strength, or otherwise. Embodiments of themini-truss thin-sheet panel assembly may, for example, be applied to anymarket sector, such as, but not limited to, solar power generation,science, structural or decorative architecture, and industry.

The preceding description has been presented with reference to variousembodiments of the invention. Persons skilled in the art and technologyto which this invention pertains will appreciate that alterations andchanges in the described structures and methods of operation can bepracticed without meaningfully departing from the principles, spirit,and scope of this invention.

1-17. (canceled)
 18. A thin-sheet panel assembly comprising: a panelcomprising a first sheet and a second sheet attached to the first sheet,the panel having a curvature such that the first sheet is substantiallyunder compression and the second sheet is substantially under tension;and a truss having the curvature and comprising a backer and a pluralityof risers formed in one piece with the backer and configured in an arrayand projecting from the backer, each riser comprising a tab extendingtransversely from the riser and being attached to the second sheet tomaintain the curvature of the panel and the truss.
 19. The panelassembly of claim 18, wherein the first sheet comprises glass.
 20. Thepanel assembly of claim 18, wherein the first sheet comprises areflective material and wherein the curvature of the first sheet isconfigured such that the first sheet reflects and focuses sunlight. 21.The panel assembly of claim 18, wherein each tab is attached to thesecond sheet with an adhesive.
 22. The panel assembly of claim 18,wherein the second sheet comprises fibers aligned with a plurality ofthe risers.
 23. The panel assembly of claim 18, wherein the second sheetcomprises a first plurality of fibers aligned with a first plurality ofthe risers and a second plurality of fibers transverse to the firstplurality of fibers and aligned with a second plurality of the risers.24. A method of manufacturing a curved thin-sheet panel assemblycomprising: forming a panel comprising attaching a first sheet to asecond sheet; forming a truss comprising a backer and a plurality ofrisers formed in one piece with the back and configured in an array andprojecting from the backer, each riser comprising a tab extendingtransversely from the riser; bending the panel to form a curved panel,having a curvature such that the first sheet is substantially undercompression and the second sheet is substantially under tension; bendingthe truss to form a curved truss having the curvature; and attaching thetabs of the risers of the second sheet to maintain the curvature of thepanel and the truss.
 25. The method of claim 24, wherein the first sheetcomprises glass.
 26. The method of claim 24, wherein the first sheetcomprises a reflective material and wherein the curvature of the firstsheet is configured such that the first sheet reflects and focusessunlight.
 27. The method of claim 24, wherein each tab is attached tothe second sheet with an adhesive.
 28. The method of claim 24, whereinthe second sheet comprises fibers aligned with a plurality of therisers.
 29. The method of claim 24, wherein the second sheet comprises afirst plurality of fibers aligned with a first plurality of the risersand a second plurality of fibers transverse to the first plurality offibers and aligned with a second plurality of the risers.
 30. A methodof manufacturing a curved thin-sheet panel assembly comprising: forminga panel comprising attaching a first sheet to a second sheet; forming atruss comprising a backer and a plurality of risers by cutting theplurality of risers from the backer sheet and bending the plurality ofrisers relative to the back sheet with a. progressive die; bending thepanel, to form a curved panel having a curvature such that the firstsheet is substantially under compression and the second sheet issubstantially under tension; bending the truss to form a curved trusshaving the curvature; and attaching the tabs of the risers of the secondsheet to maintain the curvature of the panel and the truss.
 31. Themethod of claim 30, wherein the first sheet comprises glass.
 32. Themethod of claim 30, wherein, the first sheet comprises a reflectivematerial and wherein the curvature of the first sheet is configured suchthat the first sheet reflects and focuses sunlight.
 33. The method ofclaim 30, wherein each tab is attached to the second sheet with anadhesive.
 34. The method of claim 30, wherein the second sheet comprisesfibers aligned with a plurality of the risers.
 35. The method of claim30, wherein the second sheet comprises a first plurality of fibersaligned with a first plurality of the risers and a second plurality offibers transverse to the first plurality of fibers and aligned with asecond plurality of the risers.